1. Field
The present disclosure relates to network management. More specifically, the present disclosure relates to a method and system for constructing scalable forwarding tables that reduce the number of modifications to the entries in the tables during an update.
2. Related Art
The growth of the Internet has brought with it an increasing demand for bandwidth. As a result, equipment vendors race to build larger and faster switches, each capable of supporting a large number of end devices, to move more traffic efficiently. The forwarding table in such a switch grows substantial with a large number of coupled end devices. Furthermore, an update to the forwarding table in the switch may lead to a large number of changes to the entries in the table. More importantly, because an overly large forwarding table often does not scale, simply increasing the size of a forwarding table in a switch may become unviable due to the increased complexity and operations.
Meanwhile, layer-2 (e.g., Ethernet) switching technologies continue to evolve. More routing-like functionalities, which have traditionally been the characteristics of layer-3 (e.g., Internet Protocol or IP) networks, are migrating into layer-2. Notably, the recent development of the Transparent Interconnection of Lots of Links (TRILL) protocol allows Ethernet switches to function more like routing devices. TRILL overcomes the inherent inefficiency of the conventional spanning tree protocol, which forces layer-2 switches to be coupled in a logical spanning-tree topology to avoid looping. TRILL allows routing bridges (RBridges) to be coupled in an arbitrary topology without the risk of looping by implementing routing functions in switches and including a hop count in the TRILL header.
While TRILL brings many desirable features to layer-2 networks, some issues remain unsolved when scalable and easy-to-update forwarding tables are desired.